Stationary induction apparatus



R. H. CHADWICK.

STATIONARY INDUCTIQN APPARATUS.

APPLICATION FILED FEB. 6. I919.

1,315,815. Pat'entedSept. 9, 1919.

Inventor:

Railoh H.Chadwick,

mm; fi m His Attorney.

UNITED STATES PATENT OFFICE.

RALPH H. CHADWICK, 0F FORT WAYNE, INDIANA, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION 01? NEW YORK.

STATIONARY INDUCTION APPARATUS.

Specification of Letters Patent.

Patented Sept. 9, 1919.

Application filed February 6, 1919. Serial No. 275,461.

To all whom it may concern:

Be it known that I, RALPH H. CHAoWIcK, a citizen of the United States, residing at Fort Wayne, in the county of Allen and State of Indiana, have invented certain new and useful Improvements in Stationary Induction A paratus, of which the following is a speci cation.

My invention relates t6 stationary induction apparatus and has for its object an improved construction therefor whereby a. stronger device electrically is produced in a more economical fashion than was heretofore known.

More specifically my invention relates to the construction and insulation of windings in transformers, some reactances and the like, and has for its object an arrangement of parts which will provide desired insulating characteristics where insulating media having different permittivities are employed between the various groups of windings.

It is now known that the surface of contact between two insulating media generally has less dielectric strength to resist creepage discharge thereover than the strength of either of the media taken alone; for instance, it is known in transformer construction that a discharge will take lace between a coil of the high voltage winding and a coil of the low voltage winding at a much lower voltage, if there is a surface of some solid insulation between the windings in the oil or other insulating fluid surrounding them which may be followed, than where no such surface exists as when the intervening dielectric is either wholly oil or else solid material.

The use of both solid and fluid insulating materials together in the construction 0 the type of electrical apparatus to which my invention applies is rendered necessa in order to provide both for their win mgs being mechanicall su ported in a rigid manner and for t e adequate coolin and ventilation of their windings. The isadvantages incident to this low dielectric strength for resisting cree age over the surface of contact of two die ectric media may be overcome, however, if this path is made sufliciently long to require a higher voltage to efl'ect a discharge over the surface than through the dielectric.

In the practice of my invention I have thus overcome this difficulty in a cheap and efiicacious manner by a novel arrangement of the solid insulating material between the windings which provides an extended leakage path havin the requisite resistance of crecpage. To his end I insert individual slabs of solid insulating material, symmetrically placed with respect to each other, and arranged to bear tangentially against one winding and at the same time to furnish support at their respective edges for another winding. The use of individual insulating slabs not only avoids the creepage diliiculties inherent in the use of solid dielectric material between windings, but also affords a convenient means for assembling the coils rigidly in a desired spaced relation without any other instrumentality, such as wedges; since the final slab of a given group may be sprung into place. As a further advantage, the use of individual insulating slabs permit coils of varying interior diameters to be rigidly supported in a simple manner without a complicated barrier construction.

For a more complete understanding of the nature and objects of my invention reference should be had to the following detailed description taken in connection with the accompanying drawing in which:

Figure 1 is a view partly in section and partly in elevation of a construction for transformer embodying my invention; a portion of the core construction being disassembled for the sake of clearness in the illustration. Fig. 2 is a plan view of the construction illustrated in Fig. 1. Fig. 3 is a perspective view of an assembled transformer embodying my invention. And Fig. 4 is a perspective view showing details of one form of insulating slab employed in my invention.

In the illustration of the application of my invention I have chosen a distributed core transformer because it is to the manufacture of such apparatus that I contemplate the most extended application, although chviously it is not so limited in its ap lication lating collar 12, which in turn supports the spacing elements 13; the latter bean used to-insure theproper spacing of the owermost coil 14 of the high voltage-windings 15 from the core.

The high voltage winding, in the instance illustrated, is designed to have one terminal grounded. As aconsequence it is not neces sary to have those coils adjacent the grounded terminal spaced as far from the core asthose coils adjacent the line terminal. Coil. I L-is spaced .from. the core sufiiciently to be connected to the line-lead. The other coils of winding 15 have a series of increasingilateral dimensions so that the last coils 16, the otential whose. end turns differ only slightly: from ground potential, are relatively nearer the core at all points than the coil 14.

The coils of the winding 15 also have the customary. insulating barriers 17 inserted between each other and also at the ends of the stack,

The low welt-age winding 18 is shown as a cylindrical winding which is spaced from the central leg of the core the insulating cylinder 19, but obviously this low voltage windingcan bemade in any desired or approved form. "The winding 18 is situated within and concentrically with the winding and has an exterior insulating cylinder 20 surrounding it toreinforce theinsulating jacket customarily formed about windings Inorder to insure the proper spacing of .the coils of winding 15 from the coils of winding 18 and at the same time to provide .an extended leakage path along the surface of contact between the dielectric media between the windings, I employ insulating slabs 21, here shown as four in number, symmetrically placed in order to prevent the windings becoming eocentrically disposed with respect to each other.

' These slabs 21 are made sufliciently thick when assembledandare so situated that Etheir axial central portion bears tangentially .against.th e cylinder 20, while'their edges 22 .-.are formedto bear ;against.. and retain the coils of the winding 15 in prepenspaced re- ..lation with respect to the windmg 18.

"Where" the exterior winding oils. are of varyingldiameters, as those of the high volt- .,age. windin 15, .it isnecessarythat the in slulating sla s v21' .be given a stepped forma- .tion'alon theinsupportin edges; the steps son. the ge..22, of'theysla .,2'1...being indi- ..cated at 22'. and 22.f The widest portion of. .Lthe. sI-ab. .21 thusdsupports the coils of 6Q,greatest potential. above ground, as the coil ..14,-.so:that!.these coilsnhaverthe longest .isuriace -c Z'That. pertmnof. the slab. .21, between. steps "22 and 22'. accoiidipgl snpportsctherintersm xnediete ;coils of the. high voltage minding,

the coil 17; thus inner. and: outer; reepage path. to Ithe winding 18. H i

-metri.cally disposed.

while the narrowest portion of the slab supports those coils nearest ground potential, as providing a creepage path whose length varies with the voltage to be withstood.

The disposition of the tangential spacers or slabs 21, which 'I have described, provides a su-fliciently long creepage path from a point on a coil. in the high voltage Winding to a point on the low voltage winding 1.8 which path traverses the surface of the slab 21 from. its edge to the center to require a. greater voltage for efi'eoting discharge along this path than the puncture voltage oil the dielectric media employed.

This construction I have f'ound particularly advantageous for transformers designed to furnish a constant operating source of dific'ence of potential across the electrodes of X-ray tubes, such for instance as are described in U. S. Letters Patent 1'!) Coolidge No. 1203-1 497 issued October 3! [916; since such. duty requires a transformer which shall be insulated against the relatively large difference of potential, whirh occursacross the terminals of the high voltage windings without undue bulk or weight in the transformer itself.

Having now described what is at present the best means. known to me. forcarrying out anembodiment of my invention, I would haveit understood that such .me'ans are merely illustratwe and that I, do not mean .to .be limitedthereby to the exact details shown nor in the choice of recognized equivalents except as defined in my claims hereunto appended.

What I claim as new and desire to secure by Letters Patentof the United States, is:

1. In electrical apparatus; the combination with concentric windings, of individual spacers disposed between the windings,

placed tangentially against one winding and sharing their. respective edges supporting an- .to yield. asubstantially :rigid construction.

other winding.

. 2. In electrical apparatus,- the .combination with concentric winding of a Bore. supporting the windings, and 1ndiVidnaLspacing. elements placed tangentially against the .inner winding and han ngtheirrespective tiallygagainstither Inner, groupsand, having their respective edges formed to bear against the outer groups.

4. Inelectnical apparatus, the combination with concentric windings, .cornpr s g on ,s ou rgro r in eomposedo .coi s, of a core,, and individual insulating:.,8 elements symbetween thejmier and outergrqilps pleccd tangenti l y f. th

ner group and having their respective edges formed to bear against the individual coils of the outer group.

5. In electrical apparatus, the combination with concentric windings, comprising inner and outer groups, said outer group being composed of coils of varying dlameters, of a core supporting the windings, and individual insulatin spacing elements symmetrically disposed etween the inner and outer groups, placed tangentially of the inner group and havin their respective edges formed in steps to ear against the inner surfaces of each of the coils of the outer grou i.

6. n electrical apparatus, the combination with windings supporting each other in definite spaced relations, of a plurality of different insulating media intervening between said windings, one of which comprises solid individual spacing devices for of varying diameters arranged so that their distance rom said core is Proportional to their respective potential e evations above ground, and insulating slabs placed tangentially of the low voltage winding, having their edge supporting the high voltage coils and formed to provide a cree age th whose length varies as the potential e evation of the coil supported.

8. In electrical apparatus, the combination with a distributed core, of concentric high voltage and low voltage windings mounted on the central leg thereof and adapted to be surrounded by a fluid dielectric medium said high voltage winding comprising coils of varyin diameters arranged so that their distance roin said leg is proportional to their respective potential elevations above ground, and insulating slabs immersed in said medium between said windings, placed obliquel between said windings but engaging wit each other for holding said win ings in predetermined spaced relations whereby a lon er creepage path is provided over the sur ace of sald slab than any direct puncture path between said windings.

In witness whereof, I have hereunto set my hand this 30th da of January, 1919.

RALP H. OHADWICK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner 0! Patents, w s ns n, D- G, 

